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Arrival of the Valve History from Electronics World.

Electrons - A basic education series from AEI Mazda An excellent introduction from first principles.

How the Valve Works A series of five articles from 1938.

Mullard Circuits for Audio Amplifiers Designs from Mullard's Valve application lab.

Some Important British Valves Keith Thrower's selection of landmark developments


Understanding Audio A comprehensive tutorial.

Use of Valves Safety precautions to prevent over-running.

Valve Technology A practical series of artilces published in the Maplin Magazine in 1993


Audio Amplifier Designs

Hearing is believing?

A 1 kW Audio Amplifier.

A 2E26 Class A Single Ended Amplifier. Re-purposing a VHF transmitting valve.

A 600 mW Low Power Amplifier. Employing an ECC82 push-pull output stage. Also Experimental Audio Amplifier

A 6P14 (EL84) Push Pull Stereo Amplifier. A 2020 ebay purchase reviewed. Switch mode power supply

A 6P3P (6L6) Single Ended Stereo Amplifier. A 2019 ebay purchase reviewed. Switch mode power supply


A 6P3P (6L6) Single Ended Stereo Amplifier. A 2019 ebay purchase reviewed. Conventional power supply

A 6P6P (6V6) Push Pull Stereo Amplifier. A 2019 ebay kit built and tested. Conventional power supply

A Demonstration amplifier using an AC/P and AC/Pen from 1930

An Economical 3-Valve Audio Amplifier. A basic design with valve alternatives

An EF91 Audio Amplifier.


An Experimental 33A/158M Push Pull double triode Audio Amplifier.

An Experimental 6JH8 Push Pull Audio Amplifier.

An Experimental 6V6 Single Ended Ultra Linear Audio Amplifier.

An Experimental 832A Audio Amplifier.

Audio Amplifier Testing. Sine and squre wave testing using an oscilloscope


Audio Distortion. Types of distortion and causes

Brimar 25P1 Amplifier. A 25 Watt design and praise from John Linsley Hood.

Choosing an Output Transformer.Radio Constructor, September, 1951

The Cooper-Smith Bantam 3-4 Watt Amplifier. Radio Constructor, September, 1960.

The Cooper-Smith Magnum 20 Watt Amplifier. Radio Constructor, February, 1961.


Design for a 50 Watt Amplifier - Main Amplifier. A GEC/M-OV KT88 circuit. Wireless World, April 1957

Design for a 50 Watt Amplifier - Pre Amplifier. A GEC/M-OV KT88 circuit. Wireless World, July 1957

Double Triodes and Guitar Amplification. A guide to Types and their suitability.

Double Two Audio Amplifier. A design using the ECC83 and ELL80.

Economical 50 Watt Amplifier. New ratings for KT66. Wireless World, December 1948


Experimental Audio Amplifier. ECC83 and ECC82 as push-pull output valve. Also 600 mW Low Power Amplifier

EL34-B SE stereo amplifier - Boyuu. Build and test of this Chinese amplifier kit

EL84 Class A Single-end Stereo Amplifier. Amplifier review September 2020.

From Triodes to Transistors in Hi-Fi. A paper by Mullard in 1963.

FU-32 Single Ended Stereo Amplifier. Building a Chinese amplifier kit.


A Hybrid Audio Amplifier. A 'proper' hybrid with valve output stage

High Quality 10 Watt Ultra-Linear Amplifier. A design for home construction

High Quality Audio Amplification. A chapter from Mullard circuits for audio amplifiers

High Quality Sound Reproducer. Osram 912 amplifer. Wireless World, September 1954

A Low Cost Valve Amplifier. A design from 1969 published in Practical Wireless


The 'Microamp'. A two stage SE design

The Mullard 3-3 Audio Amplifier. The original design. Also, a professionally built 3-3 amplifier

The Mullard 5-10 Audio Amplifier. The original design

The Mullard 5-20 Audio Amplifier. The original design

The Mullard ECL86 10 Watt Stereophonic Audio Amplifier. The original design


The Mullard ECL86 3 Watt Economical Stereophonic Audio Amplifier. The original design

The Mullard Stereophonic Pre-amplifier. The original design

Negative Feedback. Some pitfalls in applying it to quality amplifiers

The Neophyte Amplifier. A beginners design with full assembly details

A New Phase-Splitter. A better long-tail pair


The Osram 912 Amplifier. The circuit and GEC metal-cone loudspeaker

The (Osram) Junior Amplifier. A five Watt amplifier to complement the 912

The (Osram) Williamson Amplifier. The original design plus the revised version

A Push-Pull EL91 Audio Amplifier. A suggested circuit by G A French. A working example.

Push-Pull Balance. Effect of minor imperfections.


Push-Pull Phase Splitter. New high-gain circuit from 1947.

A QQV03-20A or QQV07-50 based Audio Amplifier. Circuit ideas for constructors.

Quality Amplifiers. Designs from Wireless World 1946 using PX4 and PX25.

The See Saw Circuit. A self balancing phase splitter.

See Saw or Paraphase. Practical points and replies to them.


Self-Balancing Push-Pull Circuits. Correction to give equal amplitudes in both halves of the load.

Simple DC Heater Supply for EF86 etc. An ingenious approach to hum reduction.

Simplifying the 'Quality Amplifier'. Wartime modifications to a well-known design.

A Small High Quality Amplifier.Using a triode push-pull transformer in a single end design

Small Audio Amplifier. Simple construction with full details


Some Notes on Phase-Splitters. Types of phase-splitters compared

Simplex Stereo Re-Visited. An experimental single valve stereo amplifier.

The Stereoplex. A simplex stereo amplifier

A Ten Watt Amplifier With Just Four Valves. A design from 1984 published in Elektor Electronics

A Three Valve 9 Watt Amplifier. A suggested design from 1960


Transformerless Output Stages Review article from February 1957

Transformerless Output Stages, More details Review article from March 1958

VA-12: A 20 Watt EL506 amplifier. A design from 1967 from Thorn-AEI Applications Laboratory. See EL506 exhibit.

Useful Push-Pull Amplifier An ECL86 design with full construction details.

Valve Technology The final article has five amplifier designs


The 'Virtuoso' Design for an 11 Watt Hi-FI amplifier

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Valve Basics

Interpretation of Valve Data

The Meaning of Valve Codes

STC Valve Codes, Mullard Receiving Valve Codes & Mullard Transmitting Valve Codes

The Cathode, Valve Cathodes, The use of Thoria , Valve Construction and Making of a Mullard Valve

The Cavity Magnetron From Wireless World May,1946


The Grid A history

Image Orthicon Camera Tubes. Principles of operation

The Diode The most basic configuration used first as a detector by Fleming .

The Triode A valve with one grid originated by de Forest .

The Bi-grid The first two grid valve.


The Tetrode The original screened grid valve. The SG Valve (explained in 1931.)

The Pentode A valve with three grids that overcame tetrode secondary emission. Patented by Mullard/Philips

The Beam Tetrode A different approach to reducing secondary emission and to circumvententing the Mullard patent.

The Hexode A valve with four grids

The Heptode The Pentagrid Converter with five grids


The Octode The valve with six grids

The Nonode The valve with seven grids

The Magic Eye The valve tuning indicator and A New Tuning Indicator the 6E5.

The Cathode-Ray Tube The heart of display systems

The Heil Tube Microwave energy generator


The Magnetron A diode in a magnetic field

The Valve The elementary principles explained - in 1923.

Velocity Modulated UHF Generators Texplaining their operation.

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General Articles

100 Metres and Below The evolution of the ultra short wave

1934 - Frequency Changing From the Mullard 1934-35 Valve catalogue

1934 - Mullard 2 Volt Battery Valves From the Mullard 1934-35 Valve catalogue

1934 - Mullard AC Mains Valves From the Mullard 1934-35 Valve catalogue

1934 - Mullard Universal Valves (AC/DC) From the Mullard 1934-35 Valve catalogue


The ABC of Television A simple explanation from 1938

AC Voltage Stabiliser A Constant voltage source for test equipment

A Dynamic Mutual Conductance (gm) Analyser The Radio Constructor, June, 1956 plus a working version

A General Purpose EF50 Circuit B9G The Radio Constructor, October, 1954

A Magnetic Digital Storage System Electronic Engineering, July, 1949


A Practical CV172 Noise Generator The Radio Constructor, August, 1956

Amplifying Crystal The Transistor: New from Bell Labs. Wireless World, October 1948

Are High-Slope Valves Wanted?

Army No. 10 Set Microwave pulse-modulated multi-channel voice link. Pulse-Width Modulation the basics explained.

Aspects of Design Application notes from Mazda. AEI 1960


Automatic Receiver Production Details of the ECME system

        Automatic Circuit Production Proposed improved system from 1956

Automatic Volume Control. Basics and the Wunderlich valve

Basic Introduction to the Valve From a beginners series in 1966

Basic Technical Aspects of Valves How a valve works


BBC Radio, Adverts and extracts from Volume 1 issue 2 of the Radio Times in October 1923.

BBC Engineering, 1922 Onward A history by Pat Leggatt. Published in 1982.

BBC Television A history of the first public service. Published in 1948.

Broadcasting Over the Mains. Published in 1941.

Cathode-Ray Amplifiers. Von Lieben's work


The Cathode Ray Microscope A 1939 article detailing the principles of operation.

The Cathode Ray Television A 1933 article and construction project for 30 line TV.

Characteristics and Distortion. Within a small signal pentode

Choke or Capacitor Input? Significance of the two systems in power supplies.

The Coherer. The mechanical RF detector


Cold Cathode Valve Basics

Colossus II lives again

Colour Television - J L Baird's 102 line demonstration

The Dawn of Broadcasting in the UK The earliest history of Radio Broadcasting

DC/AC Converter A sensitive method of measuring small DC voltages.


Deleting Hum from Audio Amplifiers Heating the first stage by RF

Eckersley's Baby Brookman's Park BBC Transmitter in 1929

Electron Multipliers An avalanche of electrons

Electronic Voltage regulators Simplified method of design, estimation of performance

Electrostatic Deflection Producing a TV raster in 1938


The Evolution of Our Photographs See how digital photography compares to film

Fantasound. Stereo for the film Fantasia

The First Airborne Radar. From a room full to a doorknob

The First All Valve Computer. The Colossus rebuild at The National Museum of Computing

Professor Sir John Ambrose Fleming


Pioneer. A short biography of Sir John Ambrose Fleming.

The Origin of the Valve. A few words from the inventor.

How I Invented the Thermionic Diode. Details from the inventor.

The First Kurhaus Radio-Concerts. Part of the history of Dutch broadcasting

First Steps in VHF Exploration. Design of a one valve super-regen receiver


Focusing Cathode Rays. An explanation of electron optics from 1954

Forward Projection in the Home. Converting a rear-projection TV Chassis

Four-Electrode Detectors. The space-charge (bi-grid) grid valve as a detector - from 1928

The Four-Electrode Valve. A one valve radio with a space-charge (bi-grid) grid valve

Frequency Changing with the Octode. Effects found on Short-Wave


The History of the UK Valve, 1904-1925 An excellent book - a 'must have'

The History of the UK Valve, 1926-1946 An excellent book

How Little Distortion can we Hear A mathematical analysis from 1957

How To Build a Two Valve Set A practical project from cigarette cards in 1929

How To Make a Valve Amplifier A practical project from cigarette cards in 1924


How To Make Your Own Wireless A practical project from cigarette cards in 1924

Klystrons and Microwave Triodes A PDF file of a 1946 book

Linear Saw-Tooth Oscillator Miller integrator and transitron oscillator

Locked Oscillator Discriminator The EH90 TV FM sound demodulator

The Lure of the Moving Coil In 1928 this was the new must have


Magnetophon Recorders Processes involved in manufacturing the tape

The Manufacture of Ebonite Materials and processes for making high-grade ebonite

Marconi the Pioneer Brief account of the early spark gap experiments

Metal Coated Valves Taken from Popular Wireless November 14, 1931.

Metals used in Valve Manufacture Taken from Vacuum Tubes by K Spangenberg (1948) 1001 .


The Miller Timebase Circuit Used with a transitron circuit to form a quality timebase

Mullard Contributions to Hearing Aids. From Mullard Outlook March, 1966.

The Mullard Valve Manufacturing Philosophy - Intrinsicality. From Mullard Outlook February, 1966.

Mullard Valve Testing - Factory and Service Department. From Mullard Outlook September, 1953 to January, 1954.

Multivibrator Action.


A New Circuit for Balancing the Characteristics of Pairs of Valves.

Obtaining High HT Voltages with Standard Transformers. Useful for triode PAs.

The Optics of Projection Television. Early 1950's Mullard system.

The Osram Miniature Valve Story. An extract from an Osram data book.

Osram Valves. The Early Days


Pin Connection aid from Mullard. A slide rule marketing aid and a way to identify unknown valves.

The PL36 in Pictures. We dissect a television line output valve.

Projection Television. Advantages of plastics for optical equipment.

Push-Pull. In 1928 a relatively new method of audio amplification in the UK.

Radiogramophonics. A 1928 series on audio reproduction.


Reaction Up-To-Date. A look again at an old technique in 1939.

Rectifiers. Not as simple as they seem.

Reliable Valves and the User. An essay on reliability, by E G Rowe of Brimar Valves.

Sealing of Glass to Other Materials. Taken from Vacuum Tubes by K Spangenberg (1948) 1001 .

Sinclair Launches Mini TV The 1983 small flat screen television


Single Valve Frequency Division Another application of the Transitron topology.

The Skin Effect A non mathematical explanation

Sound on Disc Manufacturing in 1938

Sound on Disc Vertical Cut discs in America - 1938

Squegging Oscillators Explaining their operation


Stabilisation and Smoothing with Thermionic Valves A better power supply for audio pre-amp or input stages

Stabilised Power Supplies: Part Two, Part Three & Appendix Designs by M G Scroggie, Wireless World, 1948

The Story of the Valve This makes a perfect introduction to the valve and its history

Super-Regenerative Receivers A re-assessment. Wireless World, June, 1946.

Tetrodes with Screen Feedback Further light on the Ultra-Linear circuit


The Touch of a Woman's Hand Making sub-miniature valves.

The Transitron Circuit Used with a Miller integrator to form a timebase or oscillator

Trans-Ocean Transmitters Water cooled valves for the Short Waves up to 30 MHz.

Transitron Oscillators Wide range and high frequency stability with untapped coils.

Transitron Oscillators A practical Design.


Travelling Wave Tube Amplifiers Theory and practice of these high gain microwave amplifiers

Television Progress Cathode-Ray Tube Systems - 1933

Television Reception on Band V An early look at receiving UHF signals on a domestic receiver

Ultra Linear Operation Reduced harmonic distortion in audio amplifiers

Valveholders A short article from 1930.


Valve Operated Smoothing Circuit The forerunner of the voltage stabiliser?

Valve Testers Basics of operation - 1942.

Visual Frequency Comparison A magic-eye circuit for Audio comparison.

Wireless Telephony. Marconiphone equipment from 1920's cigarette cards.

Ultra Linear Output Transformers Stability of ultra linear push-pull output stages at high frequencies

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Valve Specific Articles

The 20 kW Tube The external anode from 1922

American Loctal Valves Characteristics and dimensions - June 1939

The American Shaw Radio Tube Base.

Amplification by Secondary Emission The Mullard EE50

Acorn Antiques High Frequency Valves Ready for War


The Acorn Valves An introduction by M-OV staff in 1938

An Acorn Valve Datasheet From a valve packed in 1936

The Arcotron A cold cathode power switch

An Introduction to Valve Construction From Maplin Magazine, January, 1994.

Applications of the New Valves. Following the 1935 Radiolympia show.


The Beam Tetrode. Re-published from The BVWS Buletin Vol 33 No. 2.

The Bi-grid Valve. A needless invention?

Catkin Valves A first look - 1933.

Catkin Valves A great new development - 1933.

Cathode-Ray Tubes An explanation by M G Scroggie in 1938


Choosing a Valve Thoughts of Brian Dance in 1960

Choosing a Videcon A summary of various tubes based on the vidicon.

A Classic Unmasked The inside of an EL37 output pentode

Class B Amplification Choosing the right components for the driver stage

Class B, The First Adaptor. A add-on for battery sets in 1933.


Class B, Audio Amplifier New battery output stage

Class B, and the Driver - 1933..

Class B, Has it Come to Stay. An appraisal by MG Scroggie - 1933..

Cold Cathode Trigger Tubes What they are and how to use them

Corona Voltage Stabilisers What they are and how to use them


The De Forest DV and DL Triodes A review of these ranges

The Double-Diode Triode A new type of multi-valve - in 1933

The Early Cossor 'Tin Hat' Valves Cossor's 1922-1925 ranges

EE50 Operation A secondary emission pentode explained.

The EF80, Making thereof. Mullard produced a boxed set of components and a film


The EF91. not the valve that won the war

Electron Tubes for the Transatlantic Cable System Details of the work in the late 1940s and early 1950s

The EM34 in Pictures A range of implementations for this tuning indicator

EM87 - A new voltage-level indicator for tape recorders. From Mullard Outlook September 1961.

The Famous EF50 Valve of WW2. How Television helped the seeing eye of RADAR


Footless Valves. New Tungsram range from 1939

Frame Grid Valves. Brian Dance explains

Frame Grid Valves. Direct replacements or not?

The French 'R' Valve. The origins of the famous R Type

Gas Filled Counting Tubes. The Dekatrons


The Gated-Beam Valve. Quite special

GEC CRT Type 4051.

German Valves from WWI. An article by Andy Cowley

Grid Current and Grid Blocking. An explanation by Brian Dance

HF Pentodes. An explanation of multi-grid HF valves from 1933


Hints on Using Dull Emitter Valves (from 1924).

How valves Fail (from 1934).

Impedance-Frequency Variations in Glow-Discharge Voltage-Regulator Tubes.

Inside the 6C5G. We take one apart.

Inside the 6C5G. We take one apart.


Inside the 6J5. We take one apart.

Inside the 6J6. A broken valve explored

Inside the CV54. A broken valve explored

Inside the EF50. We take one apart.

Inside the EF37. A broken valve explored


Inside the EL37. We take one apart.

Inside the QQE03-20. A broken valve explored

Inside the QV1-150A. We take one apart.

Inside the SP61. We take one apart.

The Latest Octodes. The EK3 from 1939.


Locked-seam Cathodes A new technique for Mullard TV Valves.

Mains Drive Valves A look at the new technology for 1930.

Mazda Output Triode PP3521 A new audio output valve for DC mains sets.

Metal Striptease! We undress an American 6J5.

The Metal Valve A contemporary account of the Catkin valve.


Mullard PL500 Line Output Valve Introducing the Cavitrap anode.

Mullard Receiving Valves - General Operational Recommendations.

Mullard Red E Series Valves Review of valves new in 1938.

The Mullard Twin-Panel Picture Tube Bonded face-plate construction.

Mullard Vidicon Camera Tubes


The Murky History of the CV138 Pentode Valve

New American Valves Single-ended metal can RF Pentodes.

The New Colour Tube The precision in-line gun tube.

The New EL34 Audio Pentode. The original press release details.

New Life for Old Valves. Restoring NOS valves.


The New Mains Valves. A 1931 review of types.

New Mullard Television Valves. From Mullard Outlook in 1962.

New Tubes for Old. CRT re-gunning in 1958.

A New Tuning Indicator. The 6E5 described in 1935.

New Valves for Old Receivers. A 1934 article from Wireless World.


New Valves for Stereo Output. The ELL80 and 6DY7.

Nuvistor Valves. Innovation at the end of the valve era.

PC88 - UHF Tuner Valve. Mullard introductory description.

A PC97 Tutorial. An extract from an In Your Workshop feature.

The Pentode. A 1933 article by Stanley Mullard.


PFL200 from Mullard. A double pentode on a B10B base.

Planar Electrode Valves for VHF. A 1952 article from Wireless World.

Those Radio Rods. Valves with external control electrodes.

The Return of the Vacuum Valve. Field emission display panel development.

The Round Valves. A brief history of Captain Round's valves.


The R4, R4A, R4B and R4C. A specialist WWI valve series for heterodyne receivers.

Single Tube Colour Cameras.

SG's for Ordinary Sets. How to use a screened grid valve from 1930.

Small Power Valves. Designs for specific applications - 1955.

The Sodion Tube. Scamming around the De Forest patents.


Special Quality Valves. 1955 Progress report by Brimar engineering division.

Steel Valves. From Germany in 1938.

Storage Cathode-Ray Tube. An article from 1953 on CRTs as computer memory.

The Travelling Wave Valve. A 1946 paper by the inventor Rudolph Kompfner.

The 'Teleion'. 1945 - A versatile gas discharge relay.


The Truth About the Pentode. A 1929 essay about slow uptake in home construction.

The Tunograph. The first 'Magic Eye' tuning indicator?.

Valve Cathode Life. An article from 1951 about cathode resistance.

Valves and Their Habits. An article from 1965 on valve operating behaviour.

Valves for Band III, IV & V. An article from 1954 on UHF valve design.


Valves for Microwaves. An article from 1953 on how microwave valves work.

Valves for Radar. From Wireless World May, 1946

Valves for Single Sideband Reducing ageing in balanced modulators

Valves for Your Set A 1930s survey of types and use.

Valves in PA Equipment. An article from 1937.


Valves Galore. Series heater chains in American TV's from 1958.

Which Valve Shall I Buy? A guide from March 1924.

Wooden Crates for Large Valves. Examples.

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Subject Themes

The Cathode-Ray Tube Articles on CRTs.

Stereo? Articles on Stereophony.

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Enabling Technology Articles

The Sprengel Vacuum Pump From Chemistry World February 2008

The Gaede Diffusion Vacuum Pump From Chemistry World May 2009

Last updated June 4, 2021.
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